Effect of Prolonged Decubitus on Nitric Oxide Concentration in Chronic Obstructive Pulmonary Disease

* Bronchial obstruction in Chronic Obstructive Pulmonary Disease (COPD) is caused by inflammation of peripheral airways walls. * Neutrophils and other inflammatory mediators Interleukin-6 (IL6), Interleukin-8 (IL8), Interleukin-1 alpha (IL-1 alpha),Interleukin-1beta (IL-1 beta), Tumor Necrosis Factor alfa (TNF-alfa), Reactive Oxygen Species (ROS), Leukotriene B4 (LTB4), Nitric Oxyde (NO) are implicated in the inflammation. * Exhaled NO concentration is usually used to monitor bronchial inflammation * The relationship between decubitus and small airways behaviour is not well understood. * Our hypothesis is that cyclic opening and closure of peripheral airways during decubitus can provoke an inflammatory response which can be monitored by exhaled NO. * Data about these physiopathological aspects is missing in literature.